1. Field of the Invention
This invention relates to accoustical, thermal, and/or moisture-barrier insulating foam pre-prepared or prepared in situ from single component, moisture-curing, expanding, spreadable polyurethane compositions.
2. Statement of the Prior Art
A wide range of inorganic and organic materials is already available for accoustic and thermal insulation and moisture proofing. They are normally sold and processed as panels, sheets or half-round sections. In addition, polyurethane foams are being used to an increasing extent in this field. Polyurethane foams have the advantage over prefabricated panels, in that the insulating coating may be produced directly on the surface to be insulated and, accordingly, may readily be adapted to the available space. Unfortunately, the polyurethane foams previously used for insulating purposes, where they are two-component products, are uneconomical to use on small surfaces because of the elaborate mixing and spraying machines required. Additionally, two-component products cannot be applied to wet substrates, and may only be applied at certain temperatures. One-component products, on the other hand, have until now been applied solely from aerosol cannisters, which are limited in their size and therefore their output. Furthermore, spraying usually requires time-consuming masking of the areas not being sprayed.
U.S. Pat. No. 4,489,176--Kluth, et al., issued prior to the filing of the present application but claiming a subsequent International Convention priority date, substantially discloses the polyurethane compounds useful in this invention while disclosing utility only as an adhesive, and is incorporated herein by reference.
Polyurethane prepolymers have long been known. They are used for a variety of purposes in industry and are available in many different forms. Thus, it is known that one-component and two-component foams can be formulated on the basis of polyurethanes. Foams such as these are generally available, or may be employed, in aerosol form. Polyurethane foams of this type are described, for example, in U.S. Pat. No. 3,830,760, and corresponding published German patent application No. 20 45 852. The products cure through the diffusion of moisture and are formulated in such a way that they undergo a marked increase in volume after application, which is desirable where they are used as insulating and filling materials. Because of their large-cell, loose structure, foams such as these never attain satisfactory mechanical strength levels and therefore cannot be considered for many applications. In addition, it is difficult to obtain uniform surface application from aerosol application.
It is known from published German patent application No. 21 18 465 that polystyrene foam panels can be bonded to a sheet metal to form a roof covering, by means of an aqueous adhesive emulsion using a mineral fiber board intermediate layer permeable to water vapor. A disadvantage here is the long drying time of the emulsions which is also greatly affected by the air humidity level. Thus, in practice, additional mechanical fastenings such as nails or screws often have to be applied to prevent the insulating boards from being lifted by the effect of wind during the laying and before application of the final sealing layer.